It has heretofore been proposed to supply fuel to an internal combustion engine by means of a pressure-controlled electric-motor fuel pump and a one-way or non-return fuel line that connects the pump to fuel injectors at the engine. For example, U.S. Pat. No. 4,951,636 discloses a fuel delivery system for internal combustion engines in which an electric-motor fuel pump supplies fuel under pressure to one or more fuel injectors carried by the engine. An engine air intake manifold is carried by the engine and supplied with combustion air. A pressure sensor is responsive to a pressure differential between the fuel injector and the air intake manifold for controlling a pulse width modulated drive signal applied to the fuel pump so as to maintain substantially constant pressure differential between the fuel and combustion air across the injector. U.S. Pat. Nos. 5,001,934, 5,044,344 and 5,148,792 disclose other internal combustion engine fuel delivery systems in which fuel delivery is responsive to fuel pressure.
Among the many design criteria for internal combustion engine fuel delivery systems is the ability to provide sufficient fuel at high engine/fuel temperature conditions for starting and operation of the engine. A typical "hot soak" test for fuel delivery systems is to operate an automobile at high ambient temperature until the engine is hot, and then terminate operation of the engine, and therefore the engine cooling system, while maintaining high ambient temperature so that the engine temperature and temperature under the automobile hood increase significantly. Under these conditions, fuel within the engine fuel rail may vaporize. When it is then attempted to operate the automobile, the engine may fail to start, or if started may fail to idle or run smoothly. It is a general object of the present invention to provide a fuel delivery system and method for internal combustion engines that yield satisfactory performance under normal operating conditions and provide improved performance at high engine/fuel temperature conditions as compared with the prior art, and that are economical to manufacture and implement in a mass production environment. It is a more specific object of the present invention to provide a fuel delivery system and method of the described character that improve hot restart, idling and drive-away performance.